The key difference between chemiluminescence and fluorescence is that chemiluminescence is the light emitted as a result of a chemical reaction, whereas fluorescence is the light emitted as a result of absorption of light or electromagnetic radiation.
Chemiluminescence and fluorescence are chemical concepts that explain the light emission from different sources due to different reasons; e.g. chemical reactions or light absorption. The emitted light is named as luminescence, which refers to the spontaneous light emission from sources.
CONTENTS
1. Overview and Key Difference
2. What is Fluorescence
3. What is Chemiluminescence
4. Side by Side Comparison – Chemiluminescence vs Fluorescence in Tabular Form
5. Summary
What is Chemiluminescence?
Chemiluminescence is the emission of light as a result of a chemical reaction. Here, the emitted light is called luminescence. This means the light emits as spontaneous emission, not by heat or cold light. However, heat may also be formed. Then, the reaction becomes exothermic.
Figure 01: Chemiluminescence
During chemical reactions, the reactants collide with each other, which causes the interaction between them. Then, the reactants combine to form a transition state. The products are formed from this transition state. The transition state has the maximum enthalpy/ energy. Reactants and products have low energy. We can name the transition state as the excited state in which the electrons are excited. When the excited electrons come back to the normal energy state or the ground state, the excess energy is released in the form of photons. A beam of photons is the light we can observe during Chemiluminescence.
What is Fluorescence?
Fluorescence is the emission of light from a substance that has absorbed energy previously. These substances have to absorb light or any other electromagnetic radiation to emit light as fluorescence. Further, this emitted light is a type of luminescence, meaning it emits spontaneously. The emitted light often has a longer wavelength than the absorbed light. That means; the emitted light energy is lower than the absorbed energy.
Figure 02: Fluorescence of Proteins
During the process of fluorescence, light is emitted as a result of the excitation of atoms in the substance. The absorbed energy is often released as luminescence in a very short time period, about 10-8 seconds. That means; we can observe fluorescence as soon as we remove the source of radiation which cause the excitation.
There are many applications of fluorescence in different fields, such as mineralogy, gemology, medicine, chemical sensors, biochemical researches, dyes, biological detectors, fluorescent lamp production, etc. Moreover, we can find this process as a natural process as well; for example, in some minerals.
What is the Difference Between Chemiluminescence and Fluorescence?
Chemiluminescence and fluorescence are chemical concepts that explain light emission from different sources due to different reasons. The key difference between chemiluminescence and fluorescence is that chemiluminescence is the light emitted as a result of a chemical reaction, whereas fluorescence is the light emitted as a result of absorption of light or electromagnetic radiation.
Moreover, in chemiluminescence, electrons reach an excited state due to the energy change that occurs in a chemical reaction when it proceeds from reactants to the products. But, in fluorescence, the electrons reach an excited state due to the energy absorbed from an electromagnetic source. Besides, we can observe the emitted light after the completion of the chemical reaction in chemiluminescence. Meanwhile, in fluorescence, we can observe luminescence soon after the removal of the source of electromagnetic radiation.
Below infographic tabulates the difference between chemiluminescence and fluorescence.
Summary – Chemiluminescence vs Fluorescence
Chemiluminescence and fluorescence are chemical concepts that explain light emission from different sources due to different reasons. The key difference between chemiluminescence and fluorescence is that chemiluminescence is the light emitted as a result of a chemical reaction, whereas fluorescence is the light emitted as a result of absorption of light or electromagnetic radiation.
Reference:
1. Helmenstine, Anne Marie. “What Is Chemiluminescence?” ThoughtCo, Aug. 16, 2019, Available here.
Image Courtesy:
1. “Chemiluminescence” By Tavo Romann – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “Fluorescence from Fluorescent Proteins” By Erin Rod – Own work (CC BY-SA 4.0) via Commons Wikimedia